The present invention relates generally to shaft extension apparatus and, more particularly, to a shaft extension device for a drive mechanism of a motorcycle or the like.
In the design of vehicles, machines, and the like, it may be necessary or desirable to change the location of the driven component (e.g., a driven sprocket and shaft) with respect to the location of the driving component (e.g., a motor and drive mechanism). For instance, when normal tires are replaced by oversized tires on motorcycles having widths of 250 mm, 300 mm, or larger, it is necessary to make room for the oversized tires. The motor will often need to be moved away from the central plane of the motorcycle on which the drive mechanism lies. The larger the tires, the greater the offset is between the motor and the central plane. This requires shaft extensions for the motor comparable to the amount of the offset. Conventional ways of extending the shaft tend to be cumbersome, and can result in a substantial bending load on the extended shaft.
The present invention is directed to an apparatus and a method of providing shaft extension for a drive mechanism. Embodiments of the invention provide a bearing support for the primary drive shaft extension of a motorcycle or the like so that the main bearing support is as close to the drive mechanism as possible. The motor is coupled to a motor shaft having a given length. To extend the shaft length, a splined spacer is attached to the motor shaft. A shaft extension member having a bearing surface and a shaft extension is connected to the splined spacer. A bearing is positioned over the bearing surface of the shaft extension member. A bearing support member connects the bearing to a primary spacer. The bearing support member is attached to the front portion of the primary spacer. The rear portion of the primary spacer extends rearward to connect to the motor casing. The shaft extension apparatus can be designed for different shaft extension sizes, and can be offered as a kit to extend the shaft to a desired length for offsetting the motor to accommodate particular tire sizes. There is no need to design different jigs for different shaft extensions.
An aspect of the present invention is directed to a shaft extension device for a drive mechanism having a shaft and a motor casing. The shaft extension device comprises a shaft extension member configured to be attached to the shaft to rotate with the shaft. The shaft extension member includes a bearing surface disposed at a distance axially spaced from the shaft. A primary spacer is configured to be connected to the motor casing. A bearing is supported by the primary spacer to be axially spaced from the shaft and to contact the bearing surface of the shaft extension member to provide bearing support for the shaft extension member.
In some embodiments, a splined spacer is connected to the shaft extension member to axially space the shaft extension member from the shaft. The splined spacer has an inner splined surface configured to contact an outer splined surface of the shaft. A nut is configured to be threadingly coupled to a threaded portion of the shaft distal of the outer splined surface of the shaft. The splined spacer is detachably connected to the shaft extension member by a plurality of fasteners. The shaft extension member comprises an outer splined surface disposed distal of the bearing surface and a threaded portion disposed distal of the outer splined surface.
In specific embodiments, a bearing support member is connected to the primary spacer, and includes an inner bearing support surface configured to support the bearing. The bearing support member is detachably connected to the primary spacer by a plurality of fasteners. The primary spacer includes a plurality of inner slots. A plurality of tabs are partially received into the plurality of inner slots, and each include an aperture. The plurality of fasteners each extend through an aperture of one of the plurality of tabs to fasten the primary spacer via the plurality of tabs to the bearing support member.
In accordance with another aspect of the invention, a shaft extension device for a drive mechanism having a shaft and a motor casing comprises a shaft extension member configured to be attached to the shaft to rotate with the shaft. The shaft extension member includes a bearing surface disposed at a distance axially spaced from the shaft. A bearing support member has a bearing support surface axially spaced from the shaft. A bearing is supported by the bearing support surface of the bearing support member to be axially spaced from the shaft and to contact the bearing surface of the shaft extension member to provide bearing support for the shaft extension member.
In some embodiments, a primary spacer is configured to be attached to the motor casing, and the primary spacer is connected to the bearing support member to axially space the bearing support surface of the bearing support member from the shaft. A fastening member is configured to fasten the splined spacer to the shaft.
Another aspect of the present invention is directed to a method of providing a shaft extension for a drive mechanism having a shaft and a motor casing. The method comprises attaching a shaft extension member to the shaft for rotation with the shaft. The shaft extension member includes a bearing surface disposed at a distance axially spaced from the shaft. The method further comprises placing a bearing over the bearing surface of the shaft extension member at the distance axially spaced from the shaft, and supporting the bearing at the distance axially spaced from the shaft to generally maintain alignment of the shaft extension member with the shaft.
In some embodiments, the shaft extension member is attached to a shaft extension spacer which is connected to the shaft and axially spaces the shaft extension member from the shaft. The shaft extension spacer has an inner splined surface configured to contact an outer splined surface of the shaft, and a nut is threadingly coupled to a threaded portion of the shaft distal of the outer splined surface of the shaft to secure the shaft extension spacer to the shaft. The shaft extension member is detachably connected to the shaft extension spacer by a plurality of fasteners. The bearing is supported by a bearing support member which is connected to a primary spacer attached to the motor casing. The bearing support member is detachably connected to the primary spacer by a plurality of fasteners.